For me, the important thing in the image is the car. The corner of the shadow was cut off but I don't really notice it when comparing the before and after crops. What is apparent to me is that the car takes a more dominant role in the image and that is as it should be.

At the moment I do all my cloning work in PSPX6. The cloning tool allows for vairations in density and opacity and the donor spot can be set to move with the spot to be cloned as you move your mouse along. There is a ridge line on the bottom of the bumper. Set the cursor of the donor spot directly along the ridge and then locate further along the area you wish to clone. Hold down the left button and move the clone spot along the ridge slowly watching what you are doing. Check to make sure the ridge line in the cloned area and the original image line up and move the mouse down the line. If the result is less than pleasing undo and try again, possibly changing opacity or density. You must make sure the donor area is a good match for the area you are going to clone into or it won't work. I believe I had the opacity set for less than 100% here because you can still see the paint blemishes below the added colour. I didn't spend much time on this. The key is to match the donor area well to the area to be cloned. It is not always possible to do this well but sometimes it works out OK. When cloning doesn't work as well as I like I will also use the airbrush to paint in details if I can improve upon the results.

I do not have lr 5 and don't know if the cloning tool has been improved over lr 4.